[Maxima-bugs] assume(symbol>0) gives different result than being prompted interactively From: arielCo - 2013-06-17 03:45:17 ```When calculating the limit below, I get different results depending on whether I 'assume(t>0)' or wait for limit() to prompt and answer 'positive' (or set assume_pos:true). The result in the first case (assume(t>0)) is wrong for the problem I intend to solve, and the other result is as expected. --EXAMPLE-- (%i1) T : 1/(C1*C2*R1*R2*s^2+(R1*C2+R1*C1+R2*C2)*s+1) \$ (%i2) x : A*sin(2*%pi*f*t)*unit_step(t) \$ (%i3) X : laplace(x,t,s); 2 %pi f A (%o3) -------------- 2 2 2 4 %pi f + s (%i4) Y : X*T, C1=C, C2=C; 2 %pi f A (%o4) ------------------------------------------------------ 2 2 2 2 2 (4 %pi f + s ) (1 + s C R1 R2 + s (2 C R1 + C R2)) (%i5) assume(t>=0, C>0, f>0, R1>0, R2>0) \$ (%i6) y : ilt(Y,s,t) \$ (%i7) cir_240v: [R1=10E3, R2c=56E3, R2v=500E3, C=100E-9, Vbr=32, A=240*sqrt(2), f=60] \$ (%i8) assume(t>0) \$ (%i9) limit(y, R2, 0, plus), ratsimp; - sin(2 %pi f t) A + 4 %pi f cos(2 %pi f t) A C R1 (%o9) - -------------------------------------------------- 2 2 2 2 1 + 16 %pi f C R1 (%i10) float(%), t=0, cir_240v; (%o10) - 163.1570399304338 (%i11) forget(t>0) \$ (%i12) limit(y, R2, 0, plus), ratsimp; Is t positive or zero? positive; t - ------ 2 C R1 (%o12) - (%e (- 4 %pi f A C R1 + (- sin(2 %pi f t) A t ------ 2 C R1 2 2 2 2 + 4 %pi f cos(2 %pi f t) A C R1) %e ))/(1 + 16 %pi f C R1 ) (%i13) float(%), t=0, cir_240v; (%o13) 0.0 (%i14) build_info(); (%o14) Maxima version: "5.29.1" Maxima build date: "2012-12-29 23:14:09" Host type: "x86_64-unknown-linux-gnu" Lisp implementation type: "GNU Common Lisp (GCL)" Lisp implementation version: "GCL 2.6.7" --END OF EXAMPLE-- What am I missing? What's different between assume()-ing the fact beforehand and providing the sign interactively? Best regards, Ariel Cornejo ```